#content{
    width: 500px;
    margin: 0;
    padding: 0;
    overflow: hidden;
    font-size: 12px;
    line-height: 25px;
    border: 1px solid black;
}
ul,li{
    padding: 0;
    padding: 0;
    list-style: none;
}
/*父级元素相对定位*/
#content ul{
    position: relative;

}
.tipText,.tipBg{
    position: absolute;
    width: 500px;
    height: 25px;
    top: 350px;
}
.tipText{
    color: white;
    /*z-index: 999;*/
}
.tipBg{
    background: black;
    opacity: 0.5;  /*背景透明度*/
    /*filter: alpha(opacity=50);*/
}

